Case study: Separating source contributions of vehicle interior noise by operational transfer path analysis

The perception of vehicle interior noise is a key quality index to customers and automakers alike. By tracing noise back to key noise sources and paths, one can focus their refinement efforts. Aiming at the most efficient way to identify the primary noise sources in a vehicle cabin, this article establishes a framework of operational transfer path analysis (OTPA) for separating contributions of noise sources by operational measurements only. OTPA model design, measuring essentials and synthesis method used for separating vehicle interior noise contributions from the powertrain, tires andwindwere described in detail. To comprehend the implementation of OTPA on noise source separation, this article also addresses an exemplification study on an electric vehicle. In the case study illustrated, both spectral map and order extractions were used to validate if the OTPA synthesized results of the powertrain noise contribution agreed with the measured results. Tire noise contribution was validated using the tires driven by the dynamometer along with all other systems switched off. With well-validated OTPA model for the powertrain and tires, further individual path breakdown of the powertrain and tire noise then was investigated to identify key contributors to the interior noise. After clearly separating interior noise contributions, one therefore could design effective countermeasures to mitigate the dominant noise sources. With appropriate scheme of measurement and synthesis, the OTPA technique could therefore effectively serve target setting and refinement focus at foremost noise contributors.